Internal-combustion engine operating on the four-stroke cycle with compression ignition



March 20, 195E ARDO H. R. RIG 5 793 INTERNAL-COMBUSTION ENGINE OPERATING ON THE 2954 FOUR-STROKE CYCLE WITH COMPRESSION IGNITION Filed June 22, 1948 2 Sheets-Sheet J3,

I nvenlor Attorney March 20, 1951 H, R RICARDO 2,545,793

INTERNAL-COMBUSTION ENGINE OPERATING ON THE FOUR-STROKE CYCLE WITH COMPRESSION IGNITION Filed June 22, 1948 2 Sheets-Sheet 2 H4 F/G3 Inventor re. y

Attorney Patented Mar. 20, 1951 INTERNAL-COMBUSTEON ENGINE OPERAT- ING ON THE FOUR-STROKE CYCLE WITH COMPRESSION IGNITION Harry Ralph Ricardo, London, England, assignor to Ricardo & C0. Engineers (1927) Limited, London, Engiand, a company of Great Britain Application June 22, 1948, Serial No. 34,417 In Great Britain June 23, 1947 3 Claims.

This invention relates to internal combustion engines operating on the four-stroke cycle with compression ignition, of the kind in which there is operatively associated with two power-producing cylinders (hereinafter called working cylin ders) containing working pistons connected to the same crankshaft an air displacement cylinder (hereinafter called a pump cylinder) lying between the two working cylinders and containing a pump piston also connected to that crankshaft, the pump cylinder being provided with an inlet valve or valves for the admission of air thereto while the inlet valves of the working cylinders serveas the delivery valves of the pump cylinder, and the crank throw connected to the pump piston being displaced by 180 from the crank throws connected to the working pistons and the timingof the valves of the working cylinders being such that the power strokes of the working pistons occur alternately.

The object of the invention is to provide a satisfactory engine of the above kind operating with compression ignition.

In an internal combustion engine of the kind referred to operating with compression ignition Figure 3 is a cross-section on an enlarged scale in a plane containing the axis of one of the working cylinders and lying at right angles to the plane in which the axes of the three cylinders lie.

In the construction illustrated the engine comprises a main casing A constituting the crankcase, in which a three throw crankshaft B is according to the present invention, while the inlet and exhaust ports of the working cylinders are controlled, as in prior proposals, by poppet valves, the admission of air to the pump cylinder is controlled by a ported piston valve arranged to be reciprocated by suitable operating example as described in the present applicants British Letters Patent No. 431,345.

The invention may be carried into practice in various ways but three alternative arrangements according to the invention are illustrated somewhat diagrammatically by way of example in the accompanying drawings in which,

Figure l is a sectional elevation of one form of engine according to the invention, the section being taken in the plane containing the axes of the three cylinders,

Figure 2 is a section on the line 22 of Figure 1, and

supported in bearings B and a cylinder jacket or housing in which are carried liners C, C C constituting the cylinders proper of the engine, these liners being of the kind known as Wet liners.

Mounted upon the main casing A is a cylinder head unit D while at one end of the main casing A is a gear housing A enclosing suitable transmission gearing, for example of the silent chain type, by which rotary movement is transmitted from the crankshaft B to a layshaft E lying on one side of the engine and from which valve gearing is operated and to a fuel injection pump F on the other side of the engine. The crankshaft B, which carries a flywheel B at one end has two throws B in the same angular position with a throw B situated between them and angularly displaced from them by Each of the throws B is connected by a connecting rod to a working piston G in one of the outer 'two cylinders C and C which constitute the working cylinders, while the throw B is connected by a connecting rod Gr to a pump piston G in the central cylinder C constituting the pump cylinder.

The dimensions of the crank throw B are such in relation to those of the similar crank throw B that the stroke of the pump piston G is greater than that of either of the two working pistons G The bore of the pump cylinder C is also greater than that of each of the Working cylinder C and C so that the displacement of the piston G or each stroke is thus greater than the displacement of each of the pistons G in a ratio lying between 1.5 and 2.5.

Formed in the cylinder head unit D is a tubular housing D the axis of which lies at right angles to the plane containing the axis of the cylinders C, C C this housing containing a liner D which communicates with the interior of the cylinder 0 through a series of ports D and contains a reciprocating hollow piston valve D The interior of the valve D is in communication with the atmosphere at one end through an inlet passage D so that the ports D constitute air inlet ports controlled by the piston valve. The piston valve D is operated by a rod D connected to one arm of a bell crank lever D pivoted at D the other arm of which is connected by a connecting rod D to an eccentric E on the layshaft E.

The interior of the cylinder C also communicates through delivery ports H controlled by poppet valves H with the cylinders C and C exhaust ports H controlled by poppet valves H also communicating with this cylinder.

The poppet valves H and H thus constitute the normal inlet and exhaust valves of each of the working cylinders C and C and are operated in normal manner by rockers H which are pivoted to the cylinder head unit and acted upon by push rod and tappet mechanism H H from cams H on the layshaft E.

As will be seen from Figures 1 and 2 the arrangement is such that on its top dead centre the pump piston G approaches the cylinder head unit D as closely as mechanical considerations permit.

As will also be seen, from Figure 3, each of the cylinders C and C is provided in the cylinder head unit with a combustion chamber J of the general type, described in the present applicants British Letters Patent No. 439,426, communicating with its cylinder through a narrow passage J in a heat insulated plug and provided with a seating J for a fuel injection nozzle (not shown) to which fuel would be delivered appropriately by the fuel pump F.

The arrangement and operation of the piston valve D is such that during each suction stroke of the pump piston G air is drawn from the passage D while during each delivery stroke of the pump piston the ports D are closed. The valves H H and the fuel injection pump F are operated so that the power strokes of the piston G occur alternately, and one or other of the valves H is open during each delivery stroke of the pump piston G It will thus be seen that the piston G delivers air alternately through the ports H and that the valves H in addition to acting as the inlet valves of the working cylinders C and C act alternately as the delivery valve for the pump piston G What I claim as my invention and desire to secure by Letters Patent is:

1. An internal combustion engine operating on the four-stroke cycle with compression ignition including, in combination, a pair of similar working cylinders having inlet and exhaust ports, a pump cylinder disposed between and parallel to the working cylinders and communicating directly with the inlet ports of the working cylinders,

' working pistons and a pump piston respectively in the working cylinders and the pump cylinder, a common crank shaft to which the three pistons are connected, the crank throw connected to the pump piston being displaced by from the crank throws connected to the working pistons, and the volume displaced by one stroke of the pump piston being greater than the volume displaced by one stroke of either of the working pistons in a ratio between 1.511 and 2.511, poppet valves controlling the inlet and exhaust ports of the working cylinders, a cam shaft driven from said engine, connections between said cam shaft and said valves to drive the valves in such timed relation to the rotation of the crank shaft that the power strokes in the two working cylinders occur alternately, a cylindrical valve housing extending transversely across the upper end of the pump cylinder, communicating at one end with the atmosphere and having ports in its circumferential wall opening into the pump cylinder, a hollow ported piston valve disposed to reciprocate within the valve housing and having ports therein which communicate with the ports in the valve housing twice during each complete cycle of operation of the said ported valve, and means rotating at half crank shaft speed for reciprocating said ported valve so that it performs one complete cycle for each two revolutions of the crank shaft. 2. An internal combustion engine as claimed in claim 1 in which the means for reciprocating the piston valve comprises an eccentric carried by the cam shaft, and linkage mechanism between said eccentric and valve to operate the latter.

3. An internal combustion engine as claimed in claim 2 in which the cam shaft extends along one side of the cylinders parallel to the crank shaft,

" the operating mechanism for the poppet valves includes push rods and rockers, and the operating mechanism for the piston valve comprises a connecting rod the lower end of which engages an eccentric on the cam shaft, a lever having an approximately horizontal arm and an approximately vertical arm, means for connecting the approximately horizontal arm to the upper end of the connecting rod and means for connecting the approximately vertical arm to the reciprocating piston valve.

HARRY RALPH RICARDO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 963,788 Merrill July 12, 1910 1,048,922 Westaway Dec. 31, 1912 1,601,548 Zier et al. Sept. 28, 1926 1,634,468 Muller July 5, 1927 

